Press for treating products under high pressure



Dec. 29. 1970 Filed Dec. 5,

LANDA 3,550,199

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FNTOR. TTTTTTT N ANDA Dec. 29. 1970 T. LANDA PRESS FOR TREATING PRODUCTSUNDER HIGH PRESSURE Filed Dec. 5, 1958 L w 24 L 2 Sheets-Sheet 3.

INVENTOR. TORSTE IN LANDA BY United States Patent O 3,550,199 PRESS FORTREATING PRODUCTS UNDER HIGH PRESSURE Torstein Landa, Vaste'as, Sweden,assignor to Allmanna Svenska Elektriska Aktebolaget, Vasteras, Sweden, a

corporation of Sweden Filed Dec. 5, 1968, Ser. No. 781,543

Claims priority, application Sweden, Dec. 11, 1967,

Int. Cl. B29c 3/00; B30b 11/00; B29g 1/00 U.S. Cl. 18-5 Claims ABSTRACTOF THE DISCLOSURE A press stand has upper and lower yokes between whicha high pressure cylinder with removable end closures can be insertedwhen supported -by a movable stand. The space between the yokes isslightly greater than the length of the cylinder when the end closuresare fully inserted.

BACKGROUN D OF THE INVENTION (1) Field of the invention The presentinvention relates to a press with a preferably vertically arranged highpressure chamber having a high pressure cylinder, end closuresprojecting into this cylinder and a. press stand to take up the axialforces exerted on the end closures by a mediu-m under high pressure.Presses of the type mentioned are used, among other things, for isostatccompression of powder bodies, resistance elements, and the like atpressures in the region of 1000-10,000 bar. The cylinder is suppliedoutside the press stand with components to be treated, and then insertedin the press stand and supplied with pressure medium; It is then removedafter treatment and emptied outside the press stand.

(2) The prior art With presses of this type the high pressure chamberwith completely inserted closures must have a shoter length than thedaylight opening of the press so that the clearance necessary forinsertion and withdrawal of the chamber is obtained between the endclosures and the press. When the pressure in the chamber is increased,the end closures arefir st forced out until they come into contact withsupport surfaces in the press stand and then move only as far as thesupport surface yields under the load. Due to the friction betweenclosures and cylinder the pressure chamber is still held between thesupport surfaces of the press stand' with a considerable force even whenthe pressure is removed. This complicates removal of the pressurechamber. The end closures must therefore be returned to their innermostpositions in the cylinder so that the clearance between the end closuresand support surfaces which is suitable for handling is again obtained.

SUMMARY OF THE INVENTION With presses used hitherto this returnnecessary for removal from the press stand has caused considerableproblems. However, these are elirninated by means of the invention in amanner which enables rapid return and thus shortens the time requiredfor Operating a cycle. The invention makes it possible at low cost toincrease considerably the production in extremely expensive productionequipment.

According to the invention, the pressure chamber is axially displaceablySuspended and at least one Operating cylinder having an Operating pistonis placed below the high pressure cylinder. This Operating piston liftsthe lower end closure and the high pressure cylinder in relation to thepress stand when the Operating cylinder is supplied with pressure mediumso that the end closures are returned to their innermost positions inthe cylinder. The lower end closure is resiliently Suspended in thecylinder and is suitably supported 'by a number of spring unitsSuspended in the lower end surface of the cylinder. ln one embodimentthe spring units are completely or partly inset in a ring which supportsthe end closures. The spring units are usually made up of a number ofplate springs. The operating cylinder may consist of a cylindrical borein the end closure. The piston in the Operating cylinder may besupported by spring units Suspended in the end closure and may evencomprise return springs for the return of the piston. This spring. unitis also made up of plate springs. In one embodiment the high pressurecylinder is provided with lugs at its ends, in which are bushings 01'other guide means which can slide along a guide on a stand. Theinvention is extremely useful *for press means of the type containing acylinder Suspended on a stationary press stand and a press standarranged movably on a track so that it can be moved between an Operatingposition in which the centre lines of the press stand and the cylindersubstantially coincide and a position in which the cylinder iscompletely outside the press stand.

BRIEF DESCRIPTION OF THE DRAWINGS With the help of the accompanyingdrawings the press means according to the invention is now describedmore fully. FIG. 1 shows a side View of a high pressure chambersupported by a stationary stand and a movable press stand in a positionright outside the high pressure cylinder. FIG. 2 shows an end view andFIG. 3 a section taken along B-B according to FIG. 2 and in a positionof the press stand when the high pressure chamber is in the opening ofthe press stand. FIG. 4 shows a section through the lower part of thecylinder and the lower end closure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings 1 designates astand supporting a high pressure cylinder 2. On the stand are two lugs 3in which rods 4 are inserted. The cylinder 2 is provided with two lugs 5having journalling surfaces fitting the rods 4. The distance between theouter surfaces of the lugs 5 is less than the distance between the innersurfaces of the lugs 3. This means that the cylinder is axiallydisplaceable the same distance as the difference in distance betweensaid surfaces. The cylinder normally rests on the lower lug 3 so that agap '6 is for-med between the upper lugs 3 and 5. The cylinder 2 issealed by an upper end closure 7 and a lower end closure 8 which whichprojects a certain distance into the cylinder. The upper end closure isprovided with a ventilation channel 9. The lower end closure isresiliently Suspended in the cylinder 2 `by means of a number of springunits 10, each constructed of a number of plate springs, bolts 11 whichare screwed into threaded holes 12 in the lower flange or end surface ofthe cylinder 2, and a support ring 13 having a flange 14 abutting aflange 15 on the lower end closure 8. Through the channel 16 in the endclosure the cylinder is in communication with a pressure medium sourcenot shown in the figures. The prestressing of the spring units should atleast correspond to the weight of the end closure plus the weight of thehydraulic medium and other contents of the cylinder when this is notunder pressure. There is also a bore 17 in the end closure, in which isarranged an Operating piston 18 with a return spring 19 consisting of anumber of plate springs. The return spring is attached in the endclosure by a bolt 20 which is screwed into the threaded hole 21.Pressure medium to operate the piston 18 is supplied through the channel31. The press means comprises a displaceable press stand 22 supported bythe wheels 23 running on rails 24 set into the floor 25. The press standis of the type consisting of an upper yoke 26, a lower yoke 27, a pairof spacers 28 held together by a prestressed tape sheath 29. The pressstand is displaced between the positions shown in FIGS. 1 and 3 by meansof an Operating cylinder 30. The opening of the press is somewhat higherthan the distance between the end surfaces of the end closures whencompletely inserted. The cylinder is fixed at such a height that theclearances 33 and 34 between the yoke of the press stand and the endclosures of the cylinder are approximately equal.

The press operates in the following manner: The cylinder 2 is suppliedwith material, upper end closures are inserted and the press stand isdisplaced from the position shown in FIG. 1 to that shown in FIG. 3. Thecylinder is filled with pressure medium through the channel 16 andemptied through the channel 9 and a ValVe means, not shown. When thecylinder is filled the valve is closed and the pressure increased to thedesired level. The end closures 7 and 8 are thus pressed outwardstowards the yokes 26 and 27 which take up the pressure forces Operatingon the end closures. When the pressure is increased the stand isdeformed so that the end closures are displaced even further outwards.When the pressure is removed the stand returns to its original heightand the end closures are returned a short distance into the cylinder.The friction between seals and cylinder is, however, so great thatconsiderable force is required to push in the end closures so that evenafter complete removal of pressure the yokes engage the end closureswith a considerable force which makes removal of the press stand to theposition shown in FIG. 1 more difficult or impossible. The clearancebetween the end closures and the yokes must therefore be re-establishedbefore the press stand is moved. This is etfected with the help of theOperating piston 18 built in to the lower end r closure. When pressuremedium is supplied through the channel 31 to the bore 17 in the lowerend closure 8 the piston is pressed against the lower yoke 27 and thusfirst lifts the lower end closure until it has reached its innermostposition, that is until its stop 32 comes into contact with the endsurface of the cylinder 2. Upon continued supply of pressure medium, thepiston 18 simultaneously lifts the lower end closure 8 and the cylinderso` that the upper end closure 7 which is in contact with the upper yoke26 is pressed into the cylinder until it reaches its innermost position.The supply of pressure medium is then stopped and the bore 17 is placedthrough the channel 31 in communication with the collecting tank forpressure medium. The spring unit 19 returns the piston 18 to` theposition shown in FIG. 4 in relation to the lower end closure. Duringthe first part of the return movement the whole cylinder moves downwardsuntil the movement is stopped by the lower lug S on the cylinder meetingthe lower lug 3 in the press stand. When the piston has been completelyreturned to its inner position there are again i gaps 33 and 34` betweenthe yokes and the end closures. The press stand can now be returned tothe position shown in FIG. l, the upper end closures are removed, thecomponents taken out of the cylinder, after which this can be suppliedwith fresh material and the Operating cycle is repeated.

The invention is not limited to the embodiment shown. Several variationsand modifications are feasible within the scope of the following claims.The Operating cylinder for pressing in the end closures may, forexample, 'be placed in the lower yoke of the press stand,

I claim:

1. Press for treating products under high pressure, comprising a highpressure chamber comprising a vertical high pressure cylinder having endclosures projecting into the cylinder, a press stand having a daylightopening somewhat larger than the length of the high pressure chamberwhen the end closures are fully inserted, which stand surrounds the highpressure chamber during the compression operation and takes up the axialforces which a pressure medium in the pressure chamber eXerts on the endclosures, and means for supporting the pressure chamber in a position inwhich gaps are formed between the press stand and the end closures ofthe chamber when these end closures are inserted to their innermostpositions in the cylinder, in which said supporting means includes meansallowing the high pressure cylinder to be axially displaced and thepress comprises at least one Operating cylinder located under the highpressure cylinder and having an Operating piston which lifts the lowerend closure and the high pressure cylinder in relation to the pressstand when pressure medium is supplied to the Operating cylinder, sothat the end closures regain their innermost positions.

2. Press according to claim 1, in which the Operating cylinder and itsOperating piston are arranged inside the lower end closure.

3. Pressure means according to claim 2, in which the piston is supportedby a spring unit suspended in the end closures.

4. Pressure means according to claim 3, in which the spring unitincludes a return spring.

5. Pressure means according to claim 3, in -Which the spring unit isbuilt up of plate springs.

6. Pressure means according to claim 1, in which said supporting meanscomprises lugs at the ends of the cylinder vertically displaceable alonga guide means on a movable stand.

7. Pressure means according to claim 1, in which the lower end closureis resiliently suspended in the cylinder.

8. Pressure means according to claim 7, in which the end closure issupported by a number of spring units which are suspended in the lowerend surface of the cylinder.

9. Pressure means according to claim 8, in which the spring units are atleast partially inset in a ring which supports the end closures.

10. Pressure means according to claim 7, in which the spring units arebuilt up of plate springs.

References Cited UNITED STATES PATENTS 2,1l5,246 4/1938 Bainbridge18-16(M) 2,l2S,O68 7/1938 Dempsey l8 High pressure dgist 2,519,770 8/195 O Kramer 18 High pressure digest 2,544,414 3/1951 Bridgman et al. 1817(M) 3,l03,698 9/1963 Wollett sui 18-5(M) 3,l23,862 3/1964 Leveg, Jr18-1'6(M) 3,460,202 8/1969 Graf et al. 18-l6(M) 3,481,000 12/1969Barfuss 18 16(F) J. SPENCER OVERHOLSER, Primary Examiner R. L. SPICER,Assistant Examiner U.S. l. X.R. -269; 18-46

